diff --git a/helpers.py b/helpers.py
index 34da726..8dd0340 100644
--- a/helpers.py
+++ b/helpers.py
@@ -5,7 +5,7 @@
 
 from osgeo import ogr
 from qgis.PyQt.QtCore import QCoreApplication
-from qgis.core import QgsExpressionContextUtils, QgsSettings, QgsMapLayer, QgsMapLayerType, QgsVectorLayer,\
+from qgis.core import Qgis, QgsExpressionContextUtils, QgsSettings, QgsMapLayer, QgsMapLayerType, QgsVectorLayer,\
     QgsWkbTypes
 from qgis.utils import iface
 
@@ -180,8 +180,26 @@ def warnAboutCurveGeoms(layers: Iterable[QgsMapLayer]):
     for layer in layers:
         if not isLayerSupported(layer):
             continue
+        # additional exceptions due to missing support for curve geometries in ogr's spatialite-based spatial filtering
+        # https://github.com/WhereGroup/spatial_filter/issues/1
         if layer.storageType().upper() in ['GPKG', 'SQLITE'] and QgsWkbTypes.isCurvedType(layer.wkbType()):
-            txt = tr('The layer "{layername}" has an unsupported geometry type: '
-                     '"CircularString", "CompoundCurve", "CurvePolygon", "MultiCurve", "MultiSurface", '
-                     '"Curve" or "Surface".').format(layername=layer.name())
+            txt = tr(
+                'The {layerType} layer {layerName!r} has a geometry type ({geometryType}) that is not supported by the '
+                '{pluginName} plugin and will be ignored for filtering.'
+            ).format(
+                layerName=layer.name(),
+                layerType=layer.storageType(),
+                pluginName=LOCALIZED_PLUGIN_NAME,
+                geometryType=QgsWkbTypes.displayString(layer.wkbType()),
+            )
             iface.messageBar().pushWarning(LOCALIZED_PLUGIN_NAME, txt)
+
+
+def warnAboutQgisBugProjectSaving():
+    """Show a warning because of https://github.com/qgis/QGIS/issues/55975"""
+    if Qgis.QGIS_VERSION_INT < 33404:
+        txt = tr(
+            "QGIS &lt; 3.34.4 has a bug breaking the saving of (active) filters to projects "
+            '(<a href="https://github.com/WhereGroup/spatial_filter/issues/24">Info</a>)'
+        ).format(pluginName=LOCALIZED_PLUGIN_NAME)
+        iface.messageBar().pushWarning(LOCALIZED_PLUGIN_NAME, txt)
diff --git a/i18n/spatial_filter_de.qm b/i18n/spatial_filter_de.qm
index 71716e1..aab6b98 100644
Binary files a/i18n/spatial_filter_de.qm and b/i18n/spatial_filter_de.qm differ
diff --git a/i18n/spatial_filter_de.ts b/i18n/spatial_filter_de.ts
index 64ad7ad..aa1120b 100644
--- a/i18n/spatial_filter_de.ts
+++ b/i18n/spatial_filter_de.ts
@@ -58,16 +58,21 @@
         <source>Unknown filter</source>
         <translation>Unbekannter Filter</translation>
     </message>
-    <message>
-        <location filename="../helpers.py" line="184"/>
-        <source>The layer &quot;{layername}&quot; has an unsupported geometry type: &quot;CircularString&quot;, &quot;CompoundCurve&quot;, &quot;CurvePolygon&quot;, &quot;MultiCurve&quot;, &quot;MultiSurface&quot;, &quot;Curve&quot; or &quot;Surface&quot;.</source>
-        <translation>Der Layer &amp;quot;{layername}&amp;quot; hat einen nicht unterstützten Geometrietyp: &amp;quot;CircularString&amp;quot;, &amp;quot;CompoundCurve&amp;quot;, &amp;quot;CurvePolygon&amp;quot;, &amp;quot;MultiCurve&amp;quot;, &amp;quot;MultiSurface&amp;quot;, &amp;quot;Curve&amp;quot; oder &amp;quot;Surface&amp;quot;.</translation>
-    </message>
     <message>
         <location filename="../settings.py" line="7"/>
         <source>Spatial Filter</source>
         <translation>Räumlicher Filter</translation>
     </message>
+    <message>
+        <location filename="../helpers.py" line="186"/>
+        <source>The {layerType} layer {layerName!r} has a geometry type ({geometryType}) that is not supported by the {pluginName} plugin and will be ignored for filtering.</source>
+        <translation>Der {layerType}-Layer {layerName!r} hat einen vom {pluginName!r}-Plugin nicht unterstützten Geometrietyp ({geometryType}) und kann daher nicht gefiltert werden.</translation>
+    </message>
+    <message>
+        <location filename="../helpers.py" line="201"/>
+        <source>QGIS &amp;lt; 3.34.4 has a bug breaking the saving of (active) filters to projects (&lt;a href=&quot;https://github.com/WhereGroup/spatial_filter/issues/24&quot;&gt;Info&lt;/a&gt;)</source>
+        <translation>QGIS &amp;lt; 3.34.4 hat einen Bug, welcher beim Speichern von Projekten mit aktivem Filter zu Fehlern führt (&lt;a href=&quot;https://github.com/WhereGroup/spatial_filter/issues/24&quot;&gt;Info&lt;/a&gt;)</translation>
+    </message>
 </context>
 <context>
     <name>ExtentDialog</name>
@@ -85,27 +90,27 @@
 <context>
     <name>FilterController</name>
     <message>
-        <location filename="../controller.py" line="78"/>
+        <location filename="../controller.py" line="88"/>
         <source>Select a polygon layer</source>
         <translation>Polygonlayer auswählen</translation>
     </message>
     <message>
-        <location filename="../controller.py" line="81"/>
+        <location filename="../controller.py" line="91"/>
         <source>No features selected</source>
         <translation>Keine Features gewählt</translation>
     </message>
     <message>
-        <location filename="../controller.py" line="117"/>
+        <location filename="../controller.py" line="127"/>
         <source>Geometry is not valid</source>
         <translation>Geometrie ist ungültig</translation>
     </message>
     <message>
-        <location filename="../controller.py" line="86"/>
+        <location filename="../controller.py" line="96"/>
         <source>New filter from selection</source>
         <translation>Neuer Filter aus Auswahl</translation>
     </message>
     <message>
-        <location filename="../controller.py" line="120"/>
+        <location filename="../controller.py" line="130"/>
         <source>New filter from sketch</source>
         <translation>Neuer Filter aus Skizze</translation>
     </message>
diff --git a/metadata.txt b/metadata.txt
index bf8a845..6c1aaaa 100644
--- a/metadata.txt
+++ b/metadata.txt
@@ -17,6 +17,9 @@ hasProcessingProvider=no
 tags=python, filter, vector, postgis, performance
 
 changelog=
+    Version 1.6:
+    - Add warning on QGIS < 3.34.4 due to bug in project saving
+    - Improved warning message on unsupported geometry types
     Version 1.5:
     - Clear filter when a new project is loaded or created
     Version 1.4:
diff --git a/spatial_filter.py b/spatial_filter.py
index 888626c..f0dd92c 100644
--- a/spatial_filter.py
+++ b/spatial_filter.py
@@ -42,11 +42,15 @@ def initGui(self):
         # we import just now because we need the QCoreApplication translator
         # to be installed already (e.g. for the LOCALIZED_PLUGIN_NAME)
         from .controller import FilterController
+        from .helpers import warnAboutQgisBugProjectSaving
         from .widgets import FilterToolbar
 
         self.toolbar = FilterToolbar(FilterController(), self.iface.mainWindow())
         self.iface.mainWindow().addToolBar(self.toolbar)
 
+        warnAboutQgisBugProjectSaving()
+
+
     def unload(self):
         self.toolbar.hideFilterGeom()
         self.toolbar.controller.removeFilter()